Everything under the seat is made for the marine enviroment, however take note not to soak the mpem, just clean it by hand with a rag, and try not to soak inside the airbox either however if you do then let it sit and it will dry out, next never clean the engine when hot or warm, only clean the engine when cold, what I mean by that is temp outside does not matter I mean engine temp cold, anotherwards it has not been running. Use purple super clean to clean the engine and builge, put it in a spray bottle about 50/50 with water or as you prefer, this removes all oil and grease. Then apply a anti corrosion spray like that from crc once everything is dry, coat everything except the builge in it this way everything is easier to clean the next time.
For the air box stuff a rag in each air tube and then a plastic bag over them, this will keep water out of it.
These are cleaned just like a boat engine is, nothing to be scared of.